1. Field of the Invention
This invention relates to a defective portion detecting device, and suitably applicable to, for instance, a defective portion detecting device for detecting a defective portion of an optical-fiber cable which is used for transmission of a signal.
2. Description of the Related Art
Heretofore, in the case where a recording of a program is performed using a video camera in a studio and such, a camera-CCU system is utilized which is formed by connecting a video camera and a camera control unit (CCU) for controlling the television camera by a cable. In fact, in a camera-CCU system, a video camera is located in the studio, while a CCU is located at a distant place from the studio, for instance, a sub-control room. By the way, with respect to a camera-CCU system, the video camera is often requested to be moved to a shooting field other than a studio and used, and the CCU is requested to be placed on such a location that signal processing such as editing and transmitting of the video signal which has been shot by the video camera can be performed easily and the electric power-source can be obtained easily and used.
In the case where a video camera is moved to a shooting field, etc. from such requests, in a camera-CCU system, cables are frequently coupled together using connectors and also frequently disconnected from connectors, in order to adjust the length of the cable which connects the video camera and the CCU.
Therefore, in a camera-CCU system, by using an optical fiber as a cable, signal transmission of broad band is performed such that a signal loss due to the cable is lowered, and also miniaturization is achieved since the cable itself is lightened and the sectional area of it is diminished. That is, in a camera-CCU system, by connecting the video camera and the CCU with an optical fiber cable, the cable can be easily moved, and the signal loss due to elongation of the length of the cable can be prevented.
By the way, in a camera-CCU system of such configuration, the length of the optical fiber cable for connecting the video camera with the CCU sometimes reaches to 2000m!. Therefore, it is needed to detect whether or not the laser light which is transmitted through such length of optical fiber cable is being transmitted without a loss. In such a case, a special-purpose measuring apparatus such as an oscilloscope is usually utilized.
However, in fact, it is not easy and has poor practicality to detect a defective portion such as breaking of wire or unsatisfactory connection utilizing a special-purpose measuring apparatus such as an oscilloscope at a shooting field, etc.
Besides, in a camera-CCU system, many optical fiber cables are connected by connectors so as to connect the video camera with the CCU; so, to detect a breaking of a wire, an unsatisfactory connection, etc., it is required to ascertain the state of connection of the optical fiber cable at all connector portions; therefore, there has been such a problem that much time and much effort are needed.